1. Field of the Invention
The invention relates to a metal-sealing material-feedthrough, as well as to a component element for a solder bridge.
2. Description of the Related Art
Metal-sealing material-feedthroughs are already known in various forms from the current state of the art. They are understood to be vacuum-tight fusions of sealing materials, especially glass or synthetics to metal seals. In this type of arrangement the metals act as electric conductors. We refer you to representative documentation U.S. Pat. No. 5,345,872 A as well as to U.S. Pat. No. 3,274,937. Feedthroughs of this type are common in electronic and electrical engineering. The material used for sealing, especially glass, serves as an insulator. Typical metal-sealing material-feedthroughs are constructed such that metallic internal conductors are sealed into a pre-formed sintered glass component, whereby the sintered glass component or the glass tube is sealed into an outer casing component—the so-called base body. Regarding the usage of such feedthroughs, reference is made to the webpage of Schott North America Inc. under www.us.schott.com/epackaging. The content of this homepage is incorporated herein by reference. Feedthroughs of this type are used especially in hermetic housings for electronic components, such as for example transistors. The hermetic housings generally consist of a base plate which is formed for example by the base body of the feedthroughs, and a cover which envelops the components.
Since feedthroughs of this type also ensure a hermetic feedthrough at high pressures, feedthroughs of this type are suitable also for use in areas where high pressures occur—for example in components equipped with feedthroughs for high pressures such as pressure sensors or pyrotechnic components which are utilized in the automotive industry such as air bag ignition devices or belt tensioning devices.
Most of the aforementioned feedthroughs include two metal pins. However, more than two metal pins are also feasible. The metal-sealing material-feedthroughs generally include a base body, preferably a metal base body, for example a metal sleeve which is designed as a pivoted component. The metal base body includes at least one feedthrough opening through which at least one metal pin is inserted.
In the case of feedthroughs where there is a voltage to two metal pins it is important that the individual metallic conductors are electrically insulated when being fed through the feedthrough opening. This is achieved in that an electrically non-conductive material such as for example glass is used. Preferably at least one pin is grounded. This is achieved in that the pin is grounded to the base body.
It is known from EP 1 061 325 B1 that grounding of this type may be achieved for example with the assistance of an electrically conductive adhesive.
Alternatively a solder-coated component is suggested in EP 1 061 325 B1 which is arranged on the upper surface of the sealing material and which conductively envelops one of the two metal pins. On the other hand according to EP 1 061 325 B1 the element also contacts the metal base body, so that grounding from the metal pin to the metal component via the component enveloping the metal pin is assured. The solder material essentially ensures a conductive connection between the metal pin and component element on the one hand, and between the component element and the base body on the other hand. A disadvantage of the element in EP 1 061 325 B1 is that—based on the geometry of the component element—the gap between the component element and the inside wall of the base body increases steadily, originating from a point at which the component element and the inside wall are adjoining. If one intends to coat the component element with a solder material in order to improve the bond between component element and inside wall, then the solder material will always flow into the area in which the gap narrows, due to the solder flux. Therefore, this geometry only permits soldering over a section of a maximum of 1/10 of the circumference of the feedthrough opening. Expressed in figures this translates to a soldering along a maximum section of 1.6 mm on the inside wall of a feedthrough opening which has a diameter of 5 mm. These soldering dimensions are however frequently shorter, for example only 1.2 mm. Many times this is too short for a secure contact.
As an alternative to a connection of the metal pin with the assistance of a solder bridge over a component element it has also been demonstrated in the current state of the art to directly solder the metal pin and inside wall. This allowed soldering of sections in the range of 1.5 to 2.2 mm at a feedthrough opening diameter of 5 mm. The metal pin itself however was not occluded, so that only a one-sided connective connection existed between the metal pin and the solder material.
Neither option therefore provides a safe grounding between the metal pin and metal housing of the base body.
What is needed in the art is to improve a metal-sealing material-feedthrough to the extent that the grounding is more reliable, that the feedthrough is more reliably pressure proof and the assembly made simpler.